The present invention relates to starter generators, and more particularly to brushless wound field starter generators.
For high power, or high power density, brushless wound field starter generator applications, relatively low stator winding inductance is often necessary, in order to meet generate mode transient power quality requirements. The need for the relatively low stator winding inductance typically results in undesirable high peak phase currents during the start mode inverter operation. Accordingly, the overall generator system may be forced to operate at reduced current and power levels that provide insufficient start mode maximum torque.
Efforts to overcome the aforementioned deficiencies have included upsizing the current carrying capability of semiconductor switches in the inverter, adding an external inductor, and using feeder cables with a higher inductance. These approaches often increase overall system weight and may significantly impact the generate mode performance characteristics. Alternatively, increasing the armature leakage inductance may have significant impacts on the steady-state generate mode performance.